In order to electrically connect a conductive object such as an antenna of a smartphone to a conductive pattern of a circuit board or to electrically connect to the ground for eliminating static electricity or electromagnetic interference (EMI), an electric connecting terminal having elasticity may be used by soldering the same to the conductive pattern of the circuit board.
In particular, when used for testing an antenna contact of a smartphone or a circuit board, the electric connecting terminal is required to have low price, small size, low electric resistance, and good elasticity and elastic restoring force. In addition, for economical mounting, a reflow-solderable electric connecting terminal with vacuum pick-up may be required.
When the electric connecting terminal is used for forming a conductive path in up and down directions, in order to compensate for a vertical dimensional tolerance between a circuit board and a conductive object to be electrically connected, the electric connecting terminal is required to have an operating distance as long as possible in up and down directions and to be made from a predetermined material in a structure in which a soldering mounting is available by a surface-mount method for mass production.
For example, as a mechanical tolerance between the circuit board and the conductive object becomes greater, a longer operating distance of the electric connecting terminal is necessary to electrically connect the circuit board to the conductive object.
According to U.S. Pat. No. 7,931,475 filed by the present applicant, an elastic electric contact terminal is disclosed which includes a tube-shaped insulating elastic core, an insulating non-foam rubber coating layer adhered to the insulating elastic core to surround the insulating elastic core, and a heat-resistant polymer film having one surface adhered to the insulating non-foam rubber coating layer to surround the insulating non-foam rubber coating layer, and another surface integrally provided with a metal layer.
According to such a structure, an adhering process is included and makes a manufacturing process complicated, and there is a limit in reducing the size. In particular, when each of the diameter and height is 1 mm or shorter, it is difficult to manufacture the electric contact terminal.
As another prior art, Korean patent registration No. 1437935 filed by the present applicant discloses an electric connecting terminal including: a metal fixing member which electrically contacts an object and has a tubular shape, one end of which is open and the opening edge is bended inside to form a protrusion; a metal moveable member which is put into the fixing member to be slidably coupled and has a tubular shape, one end of which is open and the opening edge is bended outside to form a flange; and an electric conductive spring which is received in the fixing member, one end of which contacts the bottom of the fixing body, another end of which contacts the bottom of the movable member to make the movable member elastically slide to the fixing member, wherein the fixing member and the movable member are always electrically connected by the spring, the flange receives an elastic recovery force of the spring to be caught on the protrusion such that the movable member is prevented from being disengaged from the fixing member, the thickness of the flange corresponds to the thickness of the movable member, a horizontally flat plane is provided on the top surface of the movable body for vacuum pick-up, and the bottom surface of the fixing member is reflow-solderable with a solder paste.
In the foregoing structure, since a metal sheet is pressed to manufacture the movable member and the fixing member, a metallic spring is inserted therebetween, and then the fixing member is pressed again to be coupled to the movable member, it is expensive and hard to assemble.
In particular, when each of the diameter and height of the electric connecting terminal is 1 mm or smaller, since each component has small dimensions, it is hard to manufacture and assemble to result lowering of productivity.
Furthermore, in view of structure, it is hard to economically manufacture a product of which diameter or width is 0.8 mm or smaller, and there is a limit in making an operating distance long in comparison to the size.
According to another prior art of Korean patent registration No. 1330999, a probe part-connected pogo pin is disclosed in which a hollowed cylindrical opening part is formed at a bottom end of a top probe part, a bottom probe part includes an insertion part which is inserted into the opening part, a spring surrounds the inserting part and both ends thereof are fixed at the top and bottom probe parts, and the top probe part, the bottom probe part, and the spring are integrated to one body.
Since a mold cost of such a pogo pin is expensive and only one product is produced with one mold, it is hard to economically provide an electric connecting terminal having various characteristics and to manufacture a product of which each of the width and height is 0.5 mm or smaller.